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11.
Elwyn T. Reese: .... Thirty-one years is a long time! The initial reason was that we were living In the right era. Basic research was highly popular and money was readily available. Still most projects lose appeal to administrators after four or five years. Managers prefer to have something “new” to talk about.

12.
Symposium : “Enzymatic conversion of cellulosic materials: Technology and applications” “ under the auspecies of Advisory Board on Military Personnel Suplies; and U.S. Army Natick Research and Development Command”

93.
In modern commercial plants, ethanol is produced from sugar cane, corn, beets and sorghum, and on an experimental scale, from a number of other fruits, tubers, woody vegetation, etc. Fermentation yields alcohol at a concentration of 10% to 14%, after which fractional distillation becomes necessary.

94.
First-generation Ethanol There are two primary reasons why sugar cane alcohol is much better than any other biofuel: a) Productivity That is, the quantity of biomass produced per unit area is significantly larger for sugar cane than for any other plant – regardless of whether or not it is cultivated for energy biomass. In addition, the quantity of biofuel produced per unit of area,

95.
b) Energy balance (or life cycle) In other words, the ratio of energy delivered to the total energy used to produce it is much larger for sugar cane alcohol than for any other biofuel.

96.
Second-generation Ethanol Fermentation is the process by which microorganisms (yeast) convert sugar or starch into ethanol. A considerable portion of a plant, however, is neither sugar nor starch but fiber – indigestible by traditional yeasts. For sugar cane, twothirds of its mass is non-fermentable biomass fiber, and many plants contain almost no sugar or starch.

97.
What this meansis that two-thirds of sugar cane’s biomass is left out of the conversion to ethanol. Over the past two or three decades, specialists have sought to develop a number of “hydrolysis” technologies, to make it possible to convert fiber (lignin and cellulose) into ethanol.

98.
Likewise in principle it should be possible to convert any other type of crop or vegetable trash. The United States are working on a project to replace 30% of their gasoline consumption with ethanol made by hydrolysis of rejected forest products and plant matter, currently disposed of as trash.

99.
These new technologies, however, are not at all likely to be available for commercial use in fewer than 10 years. Furthermore, although they may put some other crops on a more competitive footing, they certainly will not suffice to attain yields comparable to sugar cane, which will also benefit from these innovations.

100.
In addition, Brazil has 300 million hectares of acreage suitable for sugar cane cultivation – area not occupied by forests, farm crops or protected habitats. This is equal to 100 times the area currently used for alcohol crops (3 million hectares).

101.
Part of this area was once, or is now, occupied by extensive grazing ranges. Brazil is therefore in a position to provide mankind with clean and renewable fuel with which to replace fossil fuels, and thereby make a decisive contribution to the fight against global warming. An added advantage would be the nation’s own economic development

102.
Sustainability All program choices were made for sustainability. Technologies like cogeneration, total use of bagasse and stillage, and shipping the product out through pipelines are all energy-saving technologies.

103.
Although reducing global greenhouse gas emissions is indeed central to the use of biofuels, it is nevertheless imperative that on the upstream, or production, end, environmental impacts be kept as small as possible. To that end, the NIPE study attempted an evaluation of environmental impacts upon replacement of 10% of the world’s gasoline consumption by 2025.

104.
Main source of biomass in Brasil are sugar cane bagasse (108ton/year), wood chip (107ton/year), firewood (108ton/year) and rice straw (107ton/year). In Brasil sugar cane bagasse has received more attention than the others since it is generated inside the ethanol plants, where it is used for steam and electric energy production.

112.
Recently, there is an increasing interest in using the excess of sugar cane bagasse to produce second generation ethanol. It is now known that crude bagasse is resilient to enzymatic treatment and two pre-treatments are employed: acid and steam explosion.

113.
. The first involves the heating (127ºC-30 min) of bagasse in presence of diluted acid (sulphuric or chloridric). This procedure results in rupture of polymeric fibbers and is used only in laboratory scale.

114.
The second consists in heating the bagasse at high pressure and temperature for a short period of time (about 8 min) followed by an abrupt expansion. Only few sugar/ethanol plants use this last procedure in order to produce animal food (hen and cow).